Orientador: Prof. Dr. Miguel Machinski Junior

Data da Defesa:26/02/2021


INTRODUCTION. Essential oils (EOs) are a natural mixture of volatile chemical compounds. They are known worldwide for their potent biological properties, which are attributed to the chemical constituents, mainly terpenoids and phenolic compounds. Litsea cubeba is an important medicinal plant, which is distributed in China, Japan and Southeast Asian countries. Several researchers have reported the bioactivities of L. cubeba essential oil (LCEO), including antioxidant, antimicrobial, antifungal, anti-inflammatory, insecticidal and anticancer properties. However, the applications of EOs, are limited due to its unstable to light, oxygen and temperature. Thus, an improvement in the stability of EOs is necessary, in order to expand the application fields in food, cosmetic and medicine industries. In this context, alternative strategies have been developed, such as inclusion of EOs into macromolecules. Among them, cyclodextrins are cyclic oligosaccharides with a truncated-cone shape containing glucopyranose units. The most used is β-cyclodextrin (β-CD), which contain 7 glucose units, hydrophobic cavity and hydrophilic external surface
AINS. Investigate the bioactivity of LCEO in vitro, describing its chemical profile, and assessing its potential antioxidant, cytotoxicity, antifungal and antimycotoxigenic activities against Fusarium verticillioides. Moreover, to prepare inclusion complexes with β-CD by different methods and to characterize them in terms of physicochemical properties, as well as cytotoxic effect and antifungal activity.
MATERIAL AND METHODS. To evaluate the bioactivity of LCEO, we carried out the analysis of chemical profile by gas chromatography-mass spectrometry (GC-MS), antioxidant activity by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) methods, cytotoxicity by MTT assay against HT-29 and HeLa cancer cells and antifungal and antimycotoxigenic activities against F. verticillioides. The inclusion complexes of LCEO and β-CD were prepared using physical mixture, kneading (KN) and co-precipitation (CP) methods. Moreover, the complexation efficiency and the physicochemical properties of the inclusion complexes using ATR-FTIR, FT-Raman, DSC and TG were evaluated. As well as cytotoxicity against human colorectal and cervical cancer cells and antifungal activity against Aspergillus flavus and F. verticillioides.
RESULTS AND DISCUSSION. Most of the compounds observed in the EO were neral (32.75%) and geranial (37.67%). The radical scavenging capacity of DPPH and ABTS was 104.4 and 56.4 mmol Trolox mg-1, respectively, indicating good antioxidant activity. The EO studied by us revealed cytotoxic effect against HT-29 and HeLa cancer cells. The Minimum Inhibitory and Minimum Fungicidal Concentrations against F. verticillioides were both 125 μg mL-1. Morphological investigation showed that hyphae and microconidia structures underwent changes after treatment with the EO. Analyses performed with the EO strongly reduced the mycelial development of F. verticillioides and the synthesis of fumonisins B1 and B2 in dose-dependence effect compared (p<0.01) with the fungal control (105 conidia mL-1) and positive control (fludioxonil + metalaxyl-M). The complexation efficiency results presented significant evidence of LCEO:β-CD inclusion complex formation, being KN (83%) and CP (73%) the best methods used in this study. All tested LCEO:β-CD inclusion complexes exhibited toxicity to HT-29 cells. Although, cytotoxic effect was less pronounced in HeLa tumor cell, LCEO-KN was more active against Hela than non-tumor cell. LCEO-KN and LCEO-CP inclusion complexes were efficient for both toxigenic fungi.
CONCLUSION. The results obtained in vitro suggest that LCEO has excellent antioxidant, fungicide and antimycotoxigenic effects. Moreover, the molecular inclusion of LCEO into β-CD was successful, as well as the preliminary biological results, evidencing that β-CD inclusion process may be a viable alternative to facilitate and increase future applications of this EO. Additional studies, in situ and in vivo, still need to be carried out to prove the effectiveness of LCEO as an alternative biofungicide, as well as its therapeutic potential.
KEYWORDS: Litsea cubeba essential oil; biological activities; biofungicide; molecular inclusion; β-cyclodextrin.

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